I know none of this legal to do but fun to theoretically think about.
In my corporate life of a voice engineer, working specifically with Cisco Voice in large Enterprise environments. Many large customers setup encrypted voice for Cisco IP phone to IP communication, the reasons are obvious.
Since the radios are glorified servers specifically designed to act as ham radios.
Could you combine an SDR radio, with built-in encryption so that you could conduct a conversation over the air in a secure manner ??
The other thing that had me thinking along these lines is, I've been thinking of getting a scanner but where I live most of the government agencies use encryption which makes their traffic impossible to hear with a scanner.